Bowron Daniel T
Science and Technology Facilities Council, ISIS Neutron and Muon Facility, Rutherford Appleton Laboratory, Chilton, Didcot OX11 0QX, UK.
J Synchrotron Radiat. 2018 Jul 1;25(Pt 4):981-988. doi: 10.1107/S1600577518002072. Epub 2018 May 29.
Quantitative characterization of the atomic structure of multi-component glasses is a long-standing scientific challenge. This is because in most cases no single experimental technique is capable of completely resolving all aspects of a disordered system's structure. In this situation, the most practical solution for the materials scientist is to apply multiple experimental probes offering differing degrees of insight into a material's properties. This powerful and widely adopted approach does, however, transfer the characterization challenge to the task of developing a coherent data analysis framework that can appropriately combine the diverse experimental insight into a single, data-consistent, structural model. Here, taking a terbium metaphosphate glass as an example system, it is illustrated how this can be achieved for X-ray diffraction and extended X-ray absorption fine-structure (EXAFS) spectroscopy data, using an empirical potential structure refinement approach. This methodology is based on performing a Monte Carlo simulation of the structure of a disordered material that is guided to a solution consistent with the provided experimental data, by a series of pairwise perturbation potentials operating on a classical reference potential foundation. For multi-component glasses the incorporation of EXAFS data into the resulting bulk structural models is shown to make a critical contribution that is required to properly account for the increase in local structural order that can develop in the melt-quench process of glass formation.
多组分玻璃原子结构的定量表征是一个长期存在的科学挑战。这是因为在大多数情况下，没有单一的实验技术能够完全解析无序系统结构的所有方面。在这种情况下，对于材料科学家来说，最实际的解决方案是应用多种实验探针，这些探针能对材料特性提供不同程度的洞察。然而，这种强大且被广泛采用的方法确实将表征挑战转移到了开发一个连贯的数据分析框架的任务上，该框架能够将不同的实验洞察适当地整合到一个单一的、数据一致的结构模型中。在这里，以偏磷酸铽玻璃作为示例系统，说明了如何使用经验势结构精修方法，针对X射线衍射和扩展X射线吸收精细结构（EXAFS）光谱数据实现这一点。该方法基于对无序材料结构进行蒙特卡罗模拟，通过在经典参考势基础上运行的一系列成对微扰势，引导其得到与所提供实验数据一致的解决方案。对于多组分玻璃，将EXAFS数据纳入最终的整体结构模型显示出至关重要的作用，这是正确解释在玻璃形成的熔体淬火过程中可能出现的局部结构有序度增加所必需的。
